THE SCIENCE OFFINGERPRINT

IDENTIFICATION- or -

How to Make Your Point in the Courtroom!

Prepared by:David “Ski” Witzke

Vice President, Sales & MarketingPC Pros MORE HITS ®

The Science ofFingerprint Identification

The first misconception about latent printidentification is:

Latent print examinersdon’t just count points!

So what’s my point?Latent print identification relies on threelevels of detail NOT just points!

– Level 1 detail -- Ridge flow (patterns)– Level 2 detail -- Ridge formations (ridge

endings, bifurcations, dots, or combinationsthereof)

– Level 3 detail -- Ridge path deviation (ridgestructure or formation, which includes ridgewidth, shape, pores and other details)

Level 1, 2 and 3 Details... a thumbnail explanation of terms coined by David Ashbaugh

Level 1 DetailRidge Flow

Level 1 DetailRidge Flow

Ridge flows make up threeRidge flows make up threedistinct pattern types:distinct pattern types:

•• LoopsLoops•• ArchesArches•• WhorlsWhorls

Level 1 DetailPattern Types

Left slant loopLeft slant loop

Right slant loopRight slant loop

Plain archPlain arch

Tented archTented arch

WhorlWhorl

Double Loop WhorlDouble Loop Whorl

Level 2 DetailFriction Ridge Formations

Friction skin ridges on the hands and feet createFriction skin ridges on the hands and feet createdistinctive features that are grouped into threedistinctive features that are grouped into threebasic characteristics (also known as “points”):basic characteristics (also known as “points”):

•• Bifurcations (or the splitting of a singleBifurcations (or the splitting of a singleridge into two ridges)ridge into two ridges)

•• Ridge endings (or point at which a ridgeRidge endings (or point at which a ridgeends)ends)

•• DotsDots

Level 2 DetailLevel 2 DetailFriction Ridge FormationsFriction Ridge Formations

Level 3 DetailLevel 3 Detail Ridge Path Structure Ridge Path Structure

Latent Print Examiners are allowedto make positive identifications

1. With appropriate training2. With appropriate experience3. With appropriate ability4. When using the scientific procedure of

ACE-V• Analysis• Comparison • Evaluation • Verification

The Scientific Methodologycalled ACE-V

•• AnalysisAnalysis – the qualitative and quantitative assessmentof Level 1, 2, and 3 details to determine their proportion,interrelationship and value to individualize.

•• ComparisonComparison – to examine the attributes observedduring analysis in order to determine agreement ordiscrepancies between two friction ridge impressions.

•• EvaluationEvaluation – the cyclical procedure of comparisonbetween two friction ridge impressions to effect adecision, i.e., made by the same friction skin, not madeby the same friction skin, or insufficient detail to form aconclusive decision.

•• VerificationVerification – an independent analysis, comparisonand evaluation by a second qualified examiner of thefriction ridge impressions.